1. R. J. Von Gutfeld and A. H. Nethercot, Phys. Rev. Lett. 12, 641 (1964).
2. See for example W. E. Bron, Studies of nonequilibrium dynamics in the tune domain, in: “Nonequilibrium Phonon Dynamics”, W. E. Bron, ed., Plenum, NY (1985)., W. E. Bron, Phonon generation, transport and detection through electronic states in solids, in: “Nonequilibrium Phonons in Nonmetallic Crystals,” W. Eisenmenger and A. A. Kaplyanskii, ed., North Holland, Amsterdam (1986), and W. E. Bron, Phonon transport-Experiement, in: “Dynamical Properties of Solids”, G. K. Horton and A. A. Maradudin, ed., Elsevier, Amsterdam (1990).
3. See for example W. Demtroder, “Laser Spectroscopy”, Springer, Berlin (1981).
4. G. Placzek, “Handbuch der Radiologie”, E. Marx, ed., Akademische Verlagsgesellschaft, Leipzig, (1934).
5. See for example L. L. Schiff, “Quantum Mechanics” 3rd Edition, McGraw Hill, New York (1968). See also R. Loudon, “The Quantum Theory of Light,” Clarendon Press, Oxford, 1983 146pp.